644381256425 has 12 divisors (see below), whose sum is σ = 826585612620. Its totient is φ = 497728969920.

The previous prime is 644381256419. The next prime is 644381256511. The reversal of 644381256425 is 524652183446.

It can be written as a sum of positive squares in 6 ways, for example, as 78258943504 + 566122312921 = 279748^2 + 752411^2 .

It is not a de Polignac number, because 644381256425 - 2¹⁶ = 644381190889 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 444400142 + ... + 444401591.

It is an arithmetic number, because the mean of its divisors is an integer number (68882134385).

Almost surely, 2^644381256425 is an apocalyptic number.

It is an amenable number.

644381256425 is a deficient number, since it is larger than the sum of its proper divisors (182204356195).

644381256425 is a wasteful number, since it uses less digits than its factorization.

644381256425 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 888801772 (or 888801767 counting only the distinct ones).

The product of its digits is 5529600, while the sum is 50.

The spelling of 644381256425 in words is "six hundred forty-four billion, three hundred eighty-one million, two hundred fifty-six thousand, four hundred twenty-five".